Understanding of Lithium Insertion into λ-MnO2 Compounds

1998 ◽  
Vol 548 ◽  
Author(s):  
S. Sarciaux ◽  
A. Le Gal La Salle ◽  
A. Verbaere ◽  
Y Piffard ◽  
D. Guyomard
Keyword(s):  
Oxygen Content ◽  
Structural Parameters ◽  
Reversible Capacity ◽  
Rechargeable Batteries ◽  
Structural Water ◽  
Synthesis Conditions ◽  
Starting Compound ◽  
Physico Chemical ◽  
New Compounds

ABSTRACTA large variety of EMD and HTMD samples with various oxygen and water contents and various structural parameters Pr and Mt has been prepared. We show that the physico-chemical and structural parameters of the λ-MnO2 compounds are related to the synthesis conditions. New compounds were obtained with unusual amounts of intergrowth and twinning defects.The Li insertion study focuses on a comprehensive investigation of the relationships between the material characteristics of the samples and their Li insertion behavior, and on the structural characterization of selected compounds after cycling. The oxygen content drastically affects the shape of the discharge curve after the first cycle and the total reversible capacity. The amount of structural water has an influence on the transformation kinetics of the starting phase. For optimized oxygen content (y= 2 in MnOY), the intrinsic reversible Li insertion capacity is maximum when the amount of microtwinning defects is minimum and when the structure is either mostly Ramsdellite or faulted Pyrolusite. Results show that, upon cycling, the λ-MnO2 structure seems to evoluate towards less Pyrolusite defects together with the apparition of new kinds of defects.This work shows that λ-MnO2, compounds could be good candidates for the cathode application of Li-metal rechargeable batteries, provided that the physico-chemical and structural parameters of the starting compound are well chosen.

scholarly journals Monoclinic and Orthorhombic NaMnO2 for Secondary Batteries: A Comparative Study

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1230
Author(s):  
Jessica Manzi ◽  
Annalisa Paolone ◽  
Oriele Palumbo ◽  
Domenico Corona ◽  
Arianna Massaro ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Reversible Capacity ◽  
Beta Phase ◽  
X Ray Diffraction ◽  
Positive Electrodes ◽  
Detailed Structural Analysis ◽  
Physico Chemical ◽  
Sodium Batteries ◽  
The Impact ◽  
First Time

In this manuscript, we report a detailed physico-chemical comparison between the α- and β-polymorphs of the NaMnO2 compound, a promising material for application in positive electrodes for secondary aprotic sodium batteries. In particular, the structure and vibrational properties, as well as electrochemical performance in sodium batteries, are compared to highlight differences and similarities. We exploit both laboratory techniques (Raman spectroscopy, electrochemical methods) and synchrotron radiation experiments (Fast-Fourier Transform Infrared spectroscopy, and X-ray diffraction). Notably the vibrational spectra of these phases are here reported for the first time in the literature as well as the detailed structural analysis from diffraction data. DFT+U calculations predict both phases to have similar electronic features, with structural parameters consistent with the experimental counterparts. The experimental evidence of antisite defects in the beta-phase between sodium and manganese ions is noticeable. Both polymorphs have been also tested in aprotic batteries by comparing the impact of different liquid electrolytes on the ability to de-intercalated/intercalate sodium ions. Overall, the monoclinic α-NaMnO2 shows larger reversible capacity exceeding 175 mAhg−1 at 10 mAg−1.

Synthesis and Characterization of Some New 2-Hydroxy-N-(3-Trifluoromethyl-Phenyl)-Benzamide Derivatives

2008 ◽  
Vol 59 (1) ◽  
pp. 56-60
Author(s):  
Ioana M.c. Ienascu ◽  
Alfa X. Lupea ◽  
Iuliana M. Popescu ◽  
Stefan Th. Tomas ◽  
Alina D. Zamfir
Keyword(s):  
Acetic Acid ◽  
Ethyl Ester ◽  
13C Nmr ◽  
Acid Ethyl Ester ◽  
Synthesis And Characterization ◽  
Chemical Methods ◽  
Physico Chemical ◽  
New Compounds ◽  
Benzamide Derivatives

In the reaction between 2-hydroxy-N-(3-trifluoromethyl-phenyl)-benzamide and chloro-acetic acid ethyl ester, [2-(3-trifluoromethyl-phenylcarbamoyl)-phenoxy]-acetic acid ethyl ester was obtained. The ethyl ester was condensed with hydrazine giving 2-hydrazinocarbonylmethoxy-N-(3-trifluoromethyl-phenyl)-benzamide. This hydrazide is considered the key intermediate for the synthesis of new compounds. So, in the reaction between hydrazide and chloro-substituted benzaldehydes hydrazones were obtained. In order to establish their structures, all new synthesized compounds were analyzed by modern physico-chemical methods (FTIR, 1H-NMR, 13C-NMR, MS).

Effects of synthesis conditions on dimensions, structure, and oxygen content of photocatalytically active titania nanotubes

2010 ◽  
Vol 25 (1) ◽  
pp. 89-95 ◽  
Author(s):  
Elizabeth Ranney ◽  
John Mansfield ◽  
Kai Sun ◽  
Johannes Schwank
Keyword(s):  
Oxygen Content ◽  
Uv Light ◽  
Chemical Properties ◽  
Titania Nanotubes ◽  
Nanotube Array ◽  
Synthesis Conditions ◽  
Aligned Arrays ◽  
Titania Nanotube ◽  
Physical And Chemical

In this study, we report a method for the formation and characterization of aligned arrays of amorphous titania nanotubes by anodic oxidation in thin titanium films on SiO2 substrates using fluoride-containing electrolytes. Trends in titania nanotube geometries as a function of synthesis conditions were established. A titania nanotube array surface area of approximately 178 m2/g is reported. The titania nanotubes transitioned to the rutile crystal structure when heated in air at 530 °C–705 °C. The degradation of methylene blue under UV light showed that lower fluoride concentrations in the synthesis electrolyte result in higher photocatalytic activity of the titania nanotubes. These results indicate that the synthesis conditions affect the oxygen content of amorphous nanotubes, which determines their physical and chemical properties.

A Possible Basis for Nondestructive Characterization of Ropes of Nylon 6

1997 ◽  
Vol 503 ◽  
Author(s):  
H. Jiang ◽  
M. K. Davis ◽  
R. K. Eby ◽  
P. Arsenovic
Keyword(s):  
Tensile Strength ◽  
Service Life ◽  
Fiber Diameter ◽  
Structural Parameters ◽  
Crystal Form ◽  
Nylon 6 ◽  
Remaining Service Life ◽  
Nondestructive Characterization ◽  
Fractional Content

ABSTRACTPhysical properties and structural parameters have been measured for ropes of nylon 6 as a function of the number of use operations. The fractional content of the α crystal form, sound velocity, birefringence, tensile strength and length all increase systematically and significantly with increasing the number of use operations. The fractional content of the γ crystal form and fiber diameter decrease with use. These trends indicate that the measurement of such properties and structural parameters, especially the length, provide a possible basis for establishing a reliable, rapid, and convenient nondestructive characterization method to predict the remaining service life of nylon 6 ropes.

Laboratory Methods for the Physico-Chemical Characterization of Recombinant Allergens as Reference Standards

Alergologia ◽  
2020 ◽  
Vol 1 (4) ◽  
pp. 7
Author(s):  
Mariana Vieru ◽  
Florin-Dan Popescu ◽  
Laura Haidar ◽  
Carmen Bunu-Panaitescu
Keyword(s):  
Chemical Characterization ◽  
Reference Standards ◽  
Recombinant Allergens ◽  
Laboratory Methods ◽  
Physico Chemical

Mineralogical and physico-chemical characterization of a sintered feldspathic sand

2010 ◽  
Vol 35 (5) ◽  
pp. 261-267 ◽  
Author(s):  
Wissemn Gallala ◽  
Mohamed Essghaier Gaied ◽  
Borhen Kchaou
Keyword(s):  
Chemical Characterization ◽  
Physico Chemical

SOME DIRECTIONS IN THE MODIFICATION OF AZOLES

2020 ◽  
Vol 5 (443) ◽  
pp. 85-91
Author(s):  
Ibrayev M.K., ◽  
◽  
Takibayeva A.T., ◽  
Fazylov S.D., ◽  
Rakhimberlinova Zh.B., ◽  
...  
Keyword(s):  
13C Nmr Spectroscopy ◽  
Biologically Active Compounds ◽  
Biologically Active ◽  
Active Compounds ◽  
Synthesis Conditions ◽  
Alkaloid Cytisine ◽  
Azole Ring ◽  
Cyclic Compounds ◽  
New Compounds ◽  
Derivatives Of

This article presents studies on the targeted search for new derivatives of azoles, such as benzthiazole, 3,5-dimethylpyrazole, 1,3,4-oxadiazole-2-thione, 1,3,4-thiadiazole. The possibility of combining in one molecule of the azole ring with other cyclic compounds: the alkaloid cytisine, morpholine, furan and some arenes has been studied. To obtain new compounds, the reactions of bromination, acylation, and interaction with isothiocyanates were studied. Optimal synthesis conditions were studied for all reactions. It was found that the reaction of 4-bromo-3,5-dimethylpyrazole with isothiocyanates, in contrast to the previously written derivatives of anilines, takes a longer time and requires heating the reaction mixture. The combination of a pirasol fragment with halide substituents often results in an enhanced therapeutic effect. The synthesized 2-bromine-N-(6-rodanbenzo[d]thiazole-2-yl)acetamide, due to the alkylbromide group, is an important synth in the synthesis of new benzthiazole derivatives. Its derivatives combine in one molecule the rest of rhodanbenzthiazole with alkaloid cytisine and biogenic amine morpholine and are potentially biologically active compounds, since the molecule structure contains several pharmacophoric fragments: benzthiazole and alkaloid (amine) heterocycles, rhodane and urea groups. The mechanism of formation of 1,3,4-oxadiazole-2-tyons from hydrazides under action on them by carbon disulfide was studied and assumed. It was shown that dithiocarbamates in acidic medium decompose with the release of hydrogen sulfide and the formation of highly reactive isothiocyanate group. Then, intra-molecular cyclization occurs, with the formation of end products - 1,3,4-oxadiazole-2-thions. The structures of the synthesized compounds were studied by 1H and 13C NMR spectroscopy. All synthesized substances are potentially biologically active compounds, since they contain several pharmacophore fragments in their structure.

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